The present disclosure relates spatial light modulators.
In general, a micro-mirror array (MMA) is a type of spatial light modulator (SLM) includes an array of cells, each of which includes a micro mirror that can be tilted about an axis and, furthermore, circuitry for generating electrostatic forces that tilt the micro mirror plate. In one implementation, for example, a digital mode of operation for displaying images, there are two positions at which the micro mirror plate can be tilted. The “on” position and “off” position are states of the micro-mirror in which it is stopped, and are referred to in the present specification as stopped states. In an “on” position, the micro mirror plate directs incident light to an assigned pixel of a display device. In an “off” position, the micro mirror plate direct incident light away from the display device.
A cell typically includes a first structure and a second structure configured to mechanically stop the cell's micro mirror at the “on” position and the “off” position, respectively. These structures are referred to as mechanical stops. The SLM generally operates by tilting a selected combination of micro mirrors to selectively project light to display image pixels in a display image. A display device implementing SLM-based technology is typically required to refresh images at frequencies typical of video applications. Each instance of refreshing can include the tilting of all or some of the micro mirrors to new positions. Providing fast response tilt movement by the mirrors is therefore crucial to any functional SLM-based display device. One issue with the mirror response rate is related to the stiction, i.e., contact surface adhesion, between the lower surface of the mirror and the mechanical stops, which can cause a delay in the mirror tilt response or prevent a mirror from tilting to a new orientation.